A digitally-controlled oscillator (DCO) is an electronic circuit for synthesizing a range of frequencies from a fixed reference clock. The nominal output frequency generated by a DCO is a function of the value of a digital control code. DCOs may be used as frequency synthesizers for a variety of electronic circuit-based applications. DCOs are being increasingly employed, for example, in the arenas of wireless communications, mobile digital video broadcasting, fixed cable and satellite TV tuners, digital signal processing, and a host of other radio frequency and system on-chip circuit designs.
DCO-produced waveforms may be used to implement functions such as clock and data recovery, carrier wave synthesis, signal encoding/decoding and modulation/demodulation, programmable waveform generation, and the like. Many recent applications involving wireless communications have seen the widespread use of DCOs implemented within digital phase-locked loops (DPLLs) for a radio frequency (RF) local-oscillator (LO). Due to its digital nature, the DCO can offer fast switching between output frequencies, fine frequency setting resolution, and operation over a broad frequency range. DCOs may also offer superior noise rejection over conventional circuit techniques by reducing the number of analog circuit components, and reducing or eliminating noise susceptible parameters such as oscillator control voltages.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced.